AB0641 CLINICAL BACKGROUND FACTORS RELATED TO SILENT OSTEONECROSIS OF THE FEMORAL HEAD UPON INITIATION OF STEROID THERAPY IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS
Authors: T. Kuroda, N. Tanabe, Y. Kurosawa, E. Hasegawa, A. Wakamatsu, H. Sato, D. Kobayashi, T. Nakatsue, Y. Wada, M. Nakanno, I. Narita
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Osteonecrosis of the femoral head (ONF) occurs frequently (3-40%) in patients who are treated with corticosteroids for SLE. MRI can correctly visualize pathological abnormalities of the femoral head, and it is much more sensitive than plain radiography. To analyze the risk factors associated with steroid-induced ONF, it seems important to detect early changes in the femoral head by MRI and early clinical events caused by steroid therapy. For treatment of SLE, several strategies have been selected according to the clinical conditions of patients, and there are slight differences between multicenter hospitals. In this study, the treatment performed at two hospitals, and the treatment strategy, selection of steroid, initial dose of steroid and drugs used together with steroid have been quite similar. Therefore, it should be possible to clarify the background factors associated with ONF. <h3>Objectives</h3> The purpose of this study were to clarify the factors related to silent ONF in patients with SLE and, in case of ONF, to clarify the clinical characteristics between unilateral and bilateral. <h3>Methods</h3> One hundred thirty-two patients (18 males and 114 females) with SLE were selected on the basis of having been newly diagnosed and requiring high-dose prednisolone, including pulse therapy with methylprednisolone, as the initial treatment. All the patients initially underwent plain radiography and MRI at the start of corticosteroids to detect any early changes in the femoral head. Subsequently these examinations were performed three months thereafter. The laboratory parameters were evaluated at the beginning of steroid treatment and at one month thereafter. All statistical analyses were performed with SPSS v. 13 (SPSS Inc., Chicago, IL, USA). Statistical tests were considered significant at a <i>P</i> (two sided) &lt; 0.05, and marginal significant at <i>P</i> = 0.05–0.10. Tests were 2-tailed, and differences at p &lt; 0.05 were considered significant. <h3>Results</h3> By three months after the start of corticosteroid treatment, asymptomatic ONF was diagnosed by MRI in 33 patients (25.0%), being bilateral in 21 patients and unilateral in 12. Serological activity (C3, C4, CH50 and anti-ds DNA antibody), renal function (eGFR, serum creatinine and urinary protein), anti-phospholipid antibodies, and SLEDAI were not correlated with asymptomatic ONF. BMI, BSA, and the initial dose of prednisolone per unit body weight, BMI and BSA were not correlated with silent ONF. Additionally, the occurrence of ION was not related to SLEDAI. However, patients with angiitis tended to increase the incidence of ONF (p=0.069). Patients with a higher triglyceride level both of before (p=0.002) and 4 weeks after the start of steroid treatment (p=0.004) and total cholesterol level 4 weeks after the start of steroid treatment (p=0.036) showed a significantly higher in patients with asymptomatic ONF. In patients with ONF, the level of creatinine clearance was tended to lower (p=0.062). In unilateral and bilateral studies, both anti-ds DNA antibody and C3 were not correlated. However, despite no difference in initial steroid dosage, CH50 was significantly lower and C4 was tended to lower in patients with unilateral ONF. <h3>Conclusion</h3> Asymptomatic ONF is common in patients with SLE. Both of high triglyceride and total cholesterol levels are important risk factors for ONF. In unilateral and bilateral studies, excess steroid dosage relative to serologic activity of SLE might contribute to the development of bilateral ONF. In the pathogenesis ONF, it was suggested that SLE activity and steroids are closely related. <h3>Reference</h3> [1]Kuroda T, et al. High triglyceride is a risk factor for silent osteonecrosis of the femoral head in systemic lupus erythematosus. Clin Rheumatol (2015) 34:2071–2077 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.